1. Technical Field
The invention relates to screens in general and more specifically a projection screen that allows sound to pass through the screen while video is reflected.
2. Background Art
From prior art one should refer to screens comprising a single perforated reflective front layer admitting some sound to pass through, optionally attached to a non-reflective backing layer. Loudspeakers are positioned behind the screen and the perforations admit sounds through the screen, reaching the audience. Such solutions are provided by Screen Excellence and Screen Research.
Some screen technologies use multiple layers. However these have a single reflecting layer and are designed to provide improved contrast, not density.
Density in this context refers to the structure of the fabric. High density means that the structure is finer. As for area mass, typically described in units of g/m2, it refers to the weight of the fabric. In most cases, lower weight correlates with higher density as the thread is thinner and thus the weave/knitting finer.
One should also refer to other methods for achieving sound-transparency for projection-screens. Traditionally, regular vinyl fabric was perforated with small holes to allow the sound to pass through. This technique is still used for most large cinema screens. For home theatre usage, the perforation-technology is not sufficiently good, as the holes would be too visible at short viewing-distances. Thus, various companies have utilized weaved or knitted fabric instead. This would still allow sound to pass through, meanwhile reducing the visible structure/holes in the fabric allowing for closer seating-distance.
From prior art one should refer to BE434831 regarding a sound transparent multilayer screen. However layers behind the front screen are disclosed as being diffuse, resulting in lack of sharpness.
One should also refer to JPH 11-38508 regarding a two layer light weight screen.
Finally one should refer to GB607875 regarding multilayer screens wherein some layers are dark, the purpose being to create illusions of depth.